I had my Core i5-760 stable at 4.0 GHz at 1.375v. When I upgraded to my Core i7-870, I was able to get 4.0 GHz stable at around 1.325v (or something around there). I had to play with some other voltage settings to get a stable OC with the lower VCore.

Its supposed to prevent it from dropping at stock clocks but in my experience with it overclocking it over compensates for voltage changes and will send your voltage all over the place. Disable all the intel speedstep and c1e stuff as well, then start re enabling 1 at a time till you figure out which one it is thats causing your voltage issue. A good starting point for that chip is to just set your bclk (fsb) to 200 and multiplier to 15 or so, just using the multiplier and voltages to get up to the speed you want from there and then back voltages off accordingly. Once it wont clear post you found your lowest voltage setting then play with it to find the happy medium between temp, performance and stability. Oh yeah and read the guide on ocn about it .

Hi there, before i upgraded to SB platform i was using i5 750 4ghz on MSI P55 GD80, stable for +5months without BSOD or freeze then i sold it to myfriend, i used vcore 1.28volt, Vtt 1.25volt stable IBT 20loop maximum level, btw i use 1333mhz oced to 1600mhz with 1.65volt.... all stable....btw u should set LLC to disabled, if u used enabled then when under load ur vcore will drop more lower.